1993 wrangler, speedometer not working at all. changed out speed sensor, and cluster, cannot locate problem. any ideas

Are you sure the sensor is mounted in the t-case with the correct orientation? There are three rotational 'positions', each for a different speedo tooth count range.

Also, verify that with the ign on that one of the three wires to the sensor is at +8v or so, and another at ground. The third sig return line bounces back and forth between the two others making pulses for the dash. If the wiring it right, you should be able to manually spin the speedo gear fast and see the dash gage wiggle a bit.